1. Field of the Invention:
The present invention relates to pneumatic tools used for removing and installing tension spring hose clamps used for resiliently clamping an end of a hose over a terminal portion of a tube. Still more particularly, the present invention relates to a power driven tool of the aforesaid class having the advantages of separate controls for actuation and release and high mechanical advantage via a scissor-like linkage.
2. Description of the Prior Art:
It is well known in the art to utilize resilient hose to conduct fluids. The hose is usually connected at either end to various components of a system, the connection being accomplished by slipping an end portion of the hose resiliently over a terminal portion of the tube. Ordinarily, such a press fit between the hose and the tube is not tight against leakage, especially in the event that the fluid conducted through the hose is under pressure. Accordingly, it is common practice to place an annular clamp over the hose in coaxial alignment with the tube so as to clamp the hose tightly against the tube and thereby prevent fluid leakage.
While a number of different clamps are well known, such as those which are clamped by being tightening a threaded fastener connected therewith, a very successful, simply and effective clamp is a spring tension clamp. A spring tension clamp is constructed of a resilient material and is shaped in the form of a circular loop having at either end of the loop wings which overlap each other and which are oriented more or less perpendicular to the loop. The concept of operation of spring tension clamps is that in the relaxed state the diameter of the loop in relation to that of the hose is such that the loop resiliently pinches the hose against the tube, and that by mutually squeezing together the wings, the loop diameter is caused to expand so as to permit installation or removal of the spring tension clamp with respect to the hose. To accomplish installation, the user positions of the spring tension clamp and then releases the wings, thereby resulting in the loop resiliently pinching the hose against the tube. To accomplish removal, the user mutually squeezes the wings so as to relieve clamping pressure on then hose, removes the hose from the tube, slides the spring tension clamp off the hose and then releases the wings.
A substantial amount of force is needed to mutually squeeze the wings, consequently tools are used for this purpose. It is known to use a hose clamp tool structured similarly to a pair of pliers for manually accomplishing this result. In this regard, the operator must manually apply the necessary squeezing force for the duration of time needed to squeeze the wings, a feat of hand strength that rapidly becomes tiring with each repetition. Accordingly, a power driven tool is preferred for performing repetitive clamp installation/removal tasks.
One power driven hose clamp tool is manufactured Dresser Industries of Wixom, Mich. for by Mubea Corporation of Germany, having a plant in Florence, Ky.; Mubea is, a company that is also a major supplier of spring tension clamps. This hose clamp tool is pneumatically powered and consists of a dual piston-cylinder unit which pushes a triangle shaped wedge having slots; rollers on the jaws (or ears) reside in the slots and are thereby forced open through what amounts to an incline plane mechanical linkage means.
This type of linkage has a considerable number of wearable parts, in particular there is abrasive rubbing of the wedge and the contacting jaw portion. This type of linkage has a relatively low mechanical advantage which necessitates use of a double piston system to intensify the force at the wedge from a predetermined reasonable amount of pneumatic pressure. Consequently, the German hose clamp tool is heavy, bulky, expensive to maintain, and where lighter parts such as nylon are substituted for heavier metallic parts, subject to even higher levels of parts repair and replacement.
Another disadvantage of the German tool is that the single valve control is structured so that when pneumatic pressure is established at the coupling, the jaws automatically close. Thus, the German tool tends to be dangerous for less than perfectly careful users.
Accordingly, what is needed in the art is a hose clamp tool which is safe, efficient, durable and easy to use and control.